From Halopedia, the Halo wiki
Nicole was born on December 19, 2531 in the city of New Legaspi in the state of Katagalugan on Mars. At the age of six, she was abducted by agents of the Office of Naval Intelligence and conscripted into the second class of the SPARTAN-II program.
According to her character biography, Nicole has Type O blood, and is of Filipino descent. Her hobbies include competition shooting and watching anime. She is also mentioned as liking the Filipino dessert halo-halo.
Nicole was introduced as an unlockable character for the fighting game Dead or Alive 4, with a non-canonical in-universe backstory crafted to explain her presence in the game. Team Ninja originally asked to use John-117, but Bungie declined, due to fictional constraints. Bungie and 343 Industries have confirmed that Nicole is "based on a 'real' and properly defined Spartan", but her appearance in Dead or Alive 4 is non-canonical. The extent of her character's canonicity remains unknown.
In October 2552, Nicole-458's unit was preparing for a classified mission on Nassau Station when the ONI stealth ship UNSC Apocalypso tumbled into real space – being carried along in the wake of a freak slipspace anomaly. The anomaly intersected Nassau Station, creating a semi-stable "bubble" in the space-time continuum on its way back to the 21st century. For the time being, Nicole-458 is trapped in the 21st century; she guards Nassau Station's secrets with anything but lethal force, as she realizes that killing someone in the past could have dire consequences in the future. She waits for the "bubble" to collapse and hopefully return her to the year 2552.
Nicole's movement controls were originally modeled on the character Bayman's set. Designer Tomonobu Itagaki realized a simplistic and effortless palette-swap would be boring to both fans of Dead or Alive and Halo. The Bayman moves were then treated as a starting point until the designers reinvented the Spartan as a unique and exceptional character with every move in her arsenal paying homage to a Halo move. In keeping with the idea of English being the language of the UNSC, Nicole is the only character in Dead or Alive 4 who speaks English, although she occasionally speaks Japanese. When a taunt is used Nicole smacks her fist into her open palm and activates active camo.
Nicole-458 has several unique moves. Most of them are named in reference to the Halo series.